Telegraphone apparatus and circuit



April 27,193'@.- at WOODMANSE Em 2,078,357

TELEGRAPHONE APPARATUS AND CIRCUIT Filed Nov. 25, 19:53 4 Sheets-Sh eet1' z/ a ll 0 4 1% "QI I Inventors v duomeyg April 27, 1937. GI'c.wo65MANsEE ET AL 2,078,357

TELEGRAPHONE APPARATUS AND CIRCUIT Filed Nov. 25, 1953 4 Sheets-Sheet 2/z I y 7} I A ril 27, 1937. G. c. WOODMANSEE El AL w 9 v TELEGRAPHONEAPPARATUS AND GiRcUIT File d Nov. 25, 1955 4 sheets sheet 4 InventorsPatented Apr. 27, 1937 UNITED STATES PATENT OFFICE.

$07135! TEIEGBAPHONE APPARATUS AND CIRCUIT Application November 25,1933, Serial No. 099,792

- 19 Claims.

This invention relates to telegraphone devices for recording soundmagnetically on a steel wire tively aligning the pole pieces with eachother and with the recording and reproducing wire in a telegraphone.

Another object isto provide a simple and effective telegraphonemechanism for maintaining the steel recording wire taut at all times.

Another object is to provide a simple and effective mechanism forreversing the direction of movement of the recording wire in atelegraphone.

Still another object is to provide means on a telegraphone for visuallyindicating the point longitudinally on the recording wire which ispassing through the recording and reproducing head.

The foregoing, together with other minor objects and features of theinvention will be apparent from the following detailed description whichrefers to the drawings:

In the drawings:

Fig. 1 is a plan view of a telegraphone in accordance with theinvention;

Fig. 2 is a front elevation view of the telegraphone with a portion ofthe base cut away to show'the head-supporting standard;

Fig. 3 is an end view of the telegraphone partly in section showing thedriving motor and the head-oscillating mechanism;

Fig. 4 is a detail view or a portion of the under side oi the machineshowing the driving mechanism for the wire gauge;

'Fig. 5 is a detail view at right angles to th view shown in Fig. 4taken in the plane V-V of Fig. 4; v

Fig. 6 is a cross section through the clutch for connecting the drivingmotor to the wire windingspools;

Fig. '7 is a longitudinal section through the clutch in the planeVII-VII of Fig. 6;

Fig. 8 is a detail section view of a portion. of the which are supporteda winding spool clutch mechanism taken in the curved plane VIIIVIII ofFig. 6;

Fig. 9 is a cross sectionthrough the head and supporting standard takenin the plane IX-IX of Fig. 2; p I

Fig. 10 is a detail section'through the recording and reproducing headtaken in the plane x-x of Fig. 9;

Fig; 11 is a horizontal section through the recording and reproducinghead taken in the plane 31-!!! of Fig. 2; t

Fig. 12 is a schematic diagram of an erasing and recording circuitforuse with out telegraphone.

Fig. 13 is a schematic diagram of a reproducing circuit for use with ourtelegraphone;

Fig. 14 is a detail cross section showing a modifled recording andreproducing headconstruction in which the pole piece is rigidly mountedin the coil and the coil is supported in rubber;

Fig. 15 is a detail cross section of a coil and pole piece constructionin which the pole piece is supported in rubber within the coil;

Fig. 16 is a detail cross section showing still another method ofsupporting the coil and core piece, in which the core piece is rigidlymounted within the coil and the coil is slidably mounted in the head;

Fig. 1'? is a detail cross section of a coil and core piece constructionin which the coil is rigidly mounted in the head and the core piece isslid-' .ably mounted in the coil and resiliently urged toward the wire;

Fig. 18 is a detail crosssection showing a coil Fig. 21 is a detail viewshowing core piecesof a particular shape and dimensions relative to therecording wire;

Fig. 22 is a detail view of a core piece having a hardened tip;

Fig. 23 is'a greatly enlart'ed detail cross section of a coreconstruction in which the juxtaposed core pieces are held in alignmentby interlocking sliding guides on. the respective pole pieces; and Fig.24 is a plan view oi'the structure shown in section in Fig. 23.-

Referring to Fig. 1 of the drawings, our telegraphone apparatuscomprises a base I, upon 2, a feed supported in bearing members 3 and 9,and I and II, respectively, which are supported from the base i bysuitable standards. The spools 2 and 3 may beattached to theirsupporting shafts 3 and 1, respectively, in any suitable mannerbut ithas been found convenient to provide hubs on the shafts over which thespools flt andare retained in position by means of lock nuts l2, as

shown in Fig. 2. Thus, in Fig. 3 the spool 2 is removed from shaft 5disclosing the hub 6a, this hub being provided with a pin 6b whichengages with a cooperating recess on thespool 2 to prevent relativerotation between the hub and spool when the spool is attached.

During actual recordation or reproduction of sound on or from therecordiwire 5 the latter is unwound from the feed spool 3 onto thewinding spool 2, and this movement is accomplished by applying rotatingpower to the shaft 5 through a pulley l3 keyedthereto and a belt 14 froma pulley I5 which is adapted to be connected in driving relation with adrive pulley it which is rotated through a belt I! from a pulley l8 onan electric motor l9, which motor is mounted on the under side ofthe'base I, as shown in Fig. 3.

Following the recordation or reproduction of sound by unwinding the wire5 from the feed spool 3 to the winding spool 2, the wire must be rewoundonto spool 3. This rewinding is accomplished by applying power to spool3 through shaft 1, the shaft 1 under these conditions being connected indriving relation with the pulley I3 and the latter run in the oppositedirection by reversing the electric motor I9. To apply the power of themotor automatically, either to the shaft 6 or the shaft 1, we provide anautomatic rotatably mounted upon a bearing sleeve or bushing 20 which isrigidly secured to the supporting standard 2|, and surrounds the shaft1,

the shaft 1 rotating freely withinthe bushing 20. The pulley l5, whichis belted to the pulley l3 on shaft 6, is also rotatably mounted uponthestationary bushing 20.

To establish driving connection between the pulley l6 and the pulley l5, the latter is provided with a shoulder 22 which extends within anannular recess 23 in the pulley l6, and a clutch mechanism is providedfor frictionally connecting this flange22 tothe pulley Hi. Thismechanism comprises a hardened liner ring or collar 24 secured to theinner surface of flange 22,- a

" hub 25 rigidly secured to the flange 26 of pulley I6, and a series ofballs 21 mounted in races provided in cam grooves 28 (Fig. 6) in theouter peripheral surface of the hub25. The balls 21 are retained inproper relative positions by a retainer 29 which fixes thecircumferential position of the balls relative to each other but permitsfree. radial movementthereof. Each retainer 23 is surrounded by a splitspring steel band amass? 33 which tends to retain the balls in the lowerends of the cam grooves 28. When the balls 21 are contracted within theretainer 29 by the band 30, the latter is out of engagement with thecollar 24 so'that there is no driving engagement between thehub 25 onpulley l6 and the collar 24 on pulley l5. Under these conditions theballs 21 are located in the deep ends of their associated cam grooves.28.

An exactly similar mechanism to that described ispositioned on theopposite side of the flange 26 for effecting driving engagement betweenthe pulley l6 and a member 3| which is rigidly secured to the shaft 1.Thus the member 3! is provided with an annular shoulder 32 extendinginto a recess in the pulley l6 and has secured to its inner surface ahardened ring 33. A hub 34 is rigidly secured 'to' the flange 26opposite the hub 25 and positioned concentrically within the ring 33'.Balls 35 held in position by a retainer 35 are mounted within camgrooves 31 in the hub 34, and a spring steel clip 38 is provided to urgethe balls into position within the retainer.

It will be observed from Fig. 6 that rotation of the hub "34- in acounterclockwise direction will cause the balls 35 to ride outwardly intheir of the hub 25 in a clockwise direction (relative.

to Fig. 6) tends to force the balls 21 and the clip 30 outward againstthe ring 24 to lock the hub 25 and flywheel [6 into driving relationwith the pulley l5.

To improve the operation of the clutch and make it more positive, theretainers 29 and 36, respectively, on opposite sides of the pulleyflange 26 are rigidly connected together by pins 39 (Fig. 8) whichextend through recesses 40 provided therefor in the flange 26. Thisforces .the two retainers to move together but permits them to oscillatesufllciently with respect to the 'hubs 25 and 34 to lock the hub 25 tothe ring 24- in one position and lock the hub 34 to the ring 33 in theopposite position.

This mechanism functions as follows: Assume that it is desired to drivethe winding spool 2 in clockwise direction (with respect to Fig. 2). Todo this the motor I9 is started in a clockwise direction (again with thedirection being taken with reference to Fig. 2). This accelerates thepulley IS in a clockwise direction and, since the hub 34 is rigidlyattached to the pulley l6, its corresponding movement tends to move theballs intothe deep ends of their cam grooves, there by maintaining thehub 34 out of engagement with the ring 33 and eliminating anydrivingconnection between the pulley l6 and the shaft 1. The shaft 1 is,therefore, in condition to rotate freely as the wire 5 is unwound fromspool 3. As pulley L6 accelerated in a clockwise direction, however, thecorresponding rotation of the hub 25 tended to carry the hub ahead ofthe balls 21 and the retainer 29, thereby forcing the balls 21rearwardly along their cam grooves against the clip 30 until they forcedthe clip 30 against and shaft 6.

through the medium of the belt u, pulley n Starting of the motor IS inthe opposite direction causes the clutch within pulley l6 to function inexactly the opposite manner to that just described to connect the pulleyI6 in driving relation with the shaftl and break connection betweenpulley l5 and pulley IS. The direction in which the motor I9 is drivenis controlled by varying the electrical connections (not shown 'in thedrawings) thereto in any known manner scribed and it has been found thatthis spring makes the clutch connection positive and at the same timecauses the clutch to engage smoothly, thereby preventing any jerk orshock tothedriving mechanism. v

-It is very important in a telegraphone that the steel wire bemaintained taut between the feed and wind up spools at all times becausethe wire is of very hard steel and if it becomes slack itfrequentlybreaks when the slack is taken up. Breakage of the wire hasbeen a common defect of prior telegraphones and it is very importantthat the main cause of breakage, namely, slackening of the wire, beprevented insofar as p05 sible. slackening of the wire most frequentlyoccurs when a machine is stopped before much wire has been unwound fromthe feeding spool. This is for the reason that the total weight of thewire is considerable and, if most of the wire is on the feeding spool atthe time the machine is stopped, the weight of the wire causes thefeeding spool to have a greater moment of inertia than the windingspool. Therefore, when the power is removed from the winding spool ittends to stop more quickly than the feeding spool, with the result thatwire continues to unwind from the feeding spool after the windi spoolhas stopped. We prevent continued motion of the feeding spool afterstoppage of the winding spool by so designing the driving mech-.

anism that the total moment of inertia of the driving mechanism is atall times greater than the moment of inertia of the feeding mechanismregardless of the relative amount of wire on the feeding and windingspools. The means for accomplishing this result is a flywheel 42 ofsubstantial size mounted on the shaft of the motor is (Fig. 3) mountedupon thepulley IE but we prefer to mount it on the motor shaft as inthat position it directly controls the acceleration and deceleration ofthe motor and is more or less resiliently coupled to the pulley I6 bythe belt IL The flywheel 42 is so proportioned-relative to the weightsof the spools and wire thereon that the moment of inertia of the drivingsystem is always greater than the moment of inertia of the feeding spoolregardless of the amount of wire on the latter. This flywheel functionsduring both the winding and rewinding operations since it is alwaysconnected to the spool that is pulling the wire, whether the wire isbeing wound from the feed spool 3 onto the winding spool 2 or beingrewound from the winding spool 2 onto the feed spool 3. 1 a

It will be observed from Fig. 1 that the wire 5' passes through the head4 in transit from one This flywheel, if desired, may be spool to theother. The smooth winding of the wire onto which every spool is takingup the wire is accomplished by oscillating the head 4 forwardly andrearwardly by means of a cam mechanism. This cam mechanism comprises aheartshaped cam 43 (Fig. 3) mounted upon a shaft 44 (Fig. 4) journaledin bearings 45 and 46 which are supported from the under side of thebase plate I. follower 41 (Fig. 3) mounted on a lever 43 whichCooperatingwith the cam 43 is a cam is secured to a hub 49 journaled foroscillatory movement in a bearing member 50 attached to the under sideof the base plate I. The head 4 is mounted upon a vertical standard Hwhich is also rigidly attached at its lower end to the hub 43. It willbe observed, therefore, that rotation of the cam 43 oscillates the lever48 and hub supporting standard 5| through an arc to shift the head 4back and forth between the flanges-and the spools 2 and 3 to distributethe wire on the winding spool. The cam 43 is rotated by means of abeveled gear 52 keyed to the shaft 44, which beveled gear is driven by abeveled pinion 53 Qfiounted on a vertical shaft 54, to the upper end iwhich there is keyed a worm wheel 55 which meshes with a worm 56 on theshaft 6.

When power is applied to either spool 2 or 3 to pull the wire from theother spool, the feeding spool (which as referred to here may be eitherspool 3 or spool 2) sometimes tends to run unevenly or hunt, which isobjectionable in that it tends to alternately slacken anti tighten thewire between the two spools. To produce even motion and prevent hunting,'a friction brake is provided on each spool-supporting drum. Thus,referring to Fig. 3, which discloses the-brake on the drum 6a whichsupports the spool 2, a disc I50 is secured to the drum 6a against whicha brake shoe I5I bears. This brake'shoe I5I is preferably of someresilient material, such 'as felt, and'is mounted on the end of aplunger I52 slidably supported in ferent messagesrecorded at differentpoints along the wire, it is often desired to reproduce a particularmessage. Heretofore it has only been possible to pick up the message byrunning the machine and listeningto the undesired messageuntil thedesired message was reached. In accordance with the present invention,we provide a counter 51 geared to the wire driving mechanism, whichcounter indicates visually at all times what portion of the wire 5 ispassing through the head 4.,

This counter may be of any conventional construction and is shownconnected to the spooldriving mechanism by a shaft 58 (Fig. 4) which isconnected by a pinion 59 at one end to the beveled gear 52 and. isconnected by beveled gears 60 at the other end to the driving shaft ofthe counter 51. The counter 51 may be calibrated to indicate Iapproximately the number of feet of wire that have been run off from onespool to the other or it may 'merely have an arbitrary calibration. Itis employed' in the following manner: Assume that a number of differentmessages are recorded at successive points along the wire 5. At thebegin-- ning of each recordation the reading of the counter ii will benoted. Thereafter by rewinding the I machine until'the counter againindicates this the shaft. The frame member 60 is oscillatably mounted onthe stub shaft 62 to permit oscillasame reading the operator knows thatthe wire is in position to reproduce the desired recording.

The head 4, referring to Figs. 9, 10 and 11, comprises a rear framemember 60 and a front frame member 6| each of substantial cylindricalshape and constructed of non-magnetic material, such as aluminum orbrass. The rear frame member. 60 is rotatably supported upon a stubshaft 62 which is rigidly attached by an arm 63 to the upper end of thestandard 5i. As shown in Fig. 11, the stub shaft 62 is provided with aflange or shoulder 64a on its forward end to prevent forward movement ofthe frame member 60 off tion of the head and maintain it in alignmentwith the wire 5 as the feeding spool is emptied and the winding spoolfills up. The front frame member 6! is hingedly attached to the rearframe member 60 by a hinge pin 64 passing through the lower end of.frame member BI and through a pair of arms 65 extending forwardly fromthe lower edge of the rear frame member 60. The frame members and 6| arenormally maintained in closed position, as shown in Fig. 9. by a coilspring 66 surrounding the hinge pin 64. Each frame member 60 and 6|supports a recording and reproducing coil and an erasing coil, therecording and reproducing coils in the frame membersbeing juxtaposed toeach other and the erasing coils likewise being juxtaposed to eachother'on opposite sides of the wire 5. As shown in-Fig. 11, therecording and reproducing coils provided with central bores forreceiving and supporting soft iron core pieces 69 and I0, respectively,the inner tips of which pole pieces are adapted to bear against oppositesides of the wire 5. The erasing coils are likewise mounted on spools Hand 12 in the rear and front frame members 50 and BI, respectively, andare of similar construction to the recording and reproducing coils. Asshownin Fig. 11, the front spools 58 and I2 and their core pieces 10 andM are rigidly mounted in the frame whereas the cooperating rear corepieces 69 and 13, respectively, are resiliently forced in contact withthe wire 5 by coil springs 15 and 16. Referring for the moment to Fig.9, it will be observed that the core pieces Ill leads to the recordingand reproducing and erasing coils are brought down through the hollowstandard 5|, as shown in Fig. 9. The electrical circuits employed willbe described later.

To guide the wire 5 with respect to the core pieces 69, 10, 13 and 14, apair of arms 80 and BI, respectively, are provided on the rear framemember 60,'these arms being provided with horizontal slots 83 extendinghalf way through from the front face, as shown in Figs. 2 and 11. Topermit threading of the wire through the head and thereafter lock thewire in the slots 83, a rotatably locking member 84 is provided in theouter end of each arm 80 and 8|, these locking members 84 also havingslots 85 therein, which slots may be turned into registration .with theslots 83 to admit the wire and thereafter turned bushing 98 of rubber.

outof registration with the slots, as shown in Fig. 10, to lock the wirein the head.

The general principles of operation of telegraphones are well known. Itwill sufilce at this point to state that during recordation the wire Ipasses through the head from left to right, as

shown in Fig. 11, first traversing the erasing core pieces I3 and Hwhich are magnetized to saturate the wire and thereby remove any priormagnetic records thereon. Thereafter the wire continues on past therecording core pieces 69 and III, which are variably magnetized inaccordance with voice currents in their surrounding coils and produce apermanent magnetization of the wire accordance with the voicecurrents.To rep%i i e the message recorded on the wire 5, the e rewound backontothe feed spool 3, both the erasing and recording magnets in the headbeingdeenergized during this operation so that the core pieces do noteffect the record recorded on the wire. Thereafter the wire is again fedfrom left to right through the head but this time the erasing coils aredeenergized so that they do not effect the magnetic record on the wire.At the same time the recording and reproducing coils on spools 61 and 68are connected to a telephone or loud speaker through a suitableamplifying device and as the variably magnetized wire passes through thecore pieces 69 and 10 it varies the ma etic flux therein and producescorresponding oice currents in the reproducing currents, which currentsare amplified and applied to the sound reproducer.

It is desirable in order that the maximum magnetic efiectbe produced inthe wire by the recording pole pieces and also that the maximum magneticeffect he produced in the reproducing core pieces by the wire, that thecore pieces mak direct contact with the wire. However, it as...

been found impossible to make the wire run absolutely true with respectto the pole pieces so that it has been the practice to mount the polepieces more or less loosely in their coils and force them into contactwith the wire by a spring. The scraping of the wire against the polepieces has been found to set up more or less vibration in the polepieces which tends to introduce extraneous noises. Furthermore,vibration of the core piece with respect to its coil tends to vary thefiux cutting the coil. To overcome these difficulties we. have developeda number of modified forms of construction for supporting the corepieces and coils. Thus referring to Fig. 14, we may mount the core piecerigidly.with respect to the coil spool 9| and then resiliently supportthe spool 9| in a rubber Jacket 92 which ismounted in the supportingframe member 93 of the recording and repro ucing head. Therubber 92,while permittin a certain amount of movement of the spool 9|, tends todamp out the vibration ,of the spool. The

spool may be urged towardthe wire to exert adesired pressure between thecore piece and the wire by means of an adjusting screw 94.

A modified form of construction is shown in Fig. 15 in which the spool95' is slidably mounted in the supporting frame 96 but in which the ironcore piece 91 is supported within the spool by a In this modificationalso the spool may be moved into desired position with respect to thewire by an adjusting screw 99 in the back plate of the head.

Fig. 16 discloses an arrangement in which the iron core piece I 00 isrigidly mounted with respect to the spool IM and the spool is slidablySPOOL In Fig. 1'7 there is illustrated a Construction in which a spoolIN is provided with a hollow iron core member I05 rigidly attachedthereto within which there is slidably mounted a core piece "16,-

the latter being urged toward the wire by a spring 101 at the rearthereof. A screw 108 permits adjustment ofthe spring tension. In Figs.18, 19

' and there is illustrated a form of construction in which the corepiece is laminated and is fixed to the spool, the spool being itselfmountable in the head in the manner disclosed in Fig. 16. 'It will beobserved that the center lamination I09 in Fig. 18 projects beyond theother laminations and is the portion which contacts with the wire. Thisis a desirable form of construction for the reason that it permits avery small tip for contacting with the wire while at the same timereinforcing the tip member mechanically and also reducing the totalreluctance of the core piece by increasing the total amount of ironwithin the coil without introducing serious losses from eddy currents.The shapes of the laminations and their positions are clearly indicatedin the cross section of Fig. 20.

In Figs. 14 to 20 pole pieces are shown having wire contacting tipportions of substantially larger lateral dimensions than the diameter ofthe wire with which they contact. This-construction is desirable sinceit does not necessitate accurate alignment of the pole pieces with thewire. Ordinarily, however, it is objectionable for the reason that thehard steel wire soon wears a groove in the pole piece, permittingopposite pole pieces to contact each other on each side of the wire,thereby rendering .the device substantially inoperative for the reasonthat the flux passes directly between opposite pole pieces with outpassing through the wire. Heretofore it has been considered necessary tomake the entire pole piece of very soft iron in order that it shouldhave low retentivity and permit rapid change of the magnetic flux inresponse to the voice currents. We have discovered, however, that wearon the pole pieces can be greatly reduced, and

- in fact for practical purposes substantially eliminated, withoutinterfering with the recordation and reproduction of sound, by hardeningthe tip only of the core piece, as shown in Fig. 22, in which the shadedportion llfla indicates the hardened part of the pole piece, theunshaded portion, which comprises the bulk of the magi netic material inthe core piece, being unhardened. We preferably prepare these corepieces by taking a core piece of suitable shape, as shown in Fig. 22; ofpure Norway iron and hardening the tip by first heating it in a flame,then dipping it in a carbonizing flux, again heating it, repeating thisoperation several times, and finally quenchingv the pole piece in oil orother suitable quenching material. I'his treatment has been I found tomake the wire-contacting tip of the pole piece even harder than the wirewith which it contacts without in any noticeable degree interfering withthe quality and volume of sound reproduction. In fact, the reproductionobtained with these pole pieces appears to be actually superior in someinstances to the reproducwould function satisfactorily, it has been thepractice to stagger the juxtaposed pole pieces longitudinally to preventcontact therebetween as thepole pieces became grooved by the wire. It isundesirable, however, to stagger the pole pieces for the reason that itbrings. a greater length of wire into the magnetizing field of the polepieces at any instant and-necessitates running the wire at extremelyhigh speeds in order to secure satisfactory reproduction of the higher.

voice frequencies. In accordance with the present invention, we may useoppositely positioned pole pieces of the shape shown in Fig. 21, whichpermits the pole pieces to be of mechanically soft material since thepole tips are straight and of smaller diameter than the wire. Thisconstruction permits the pole pieces to be worn away for a substantialdistance before they can be grooved by the wire to come in contact witheach other.

An obvious defect of the pole piece construction shown in Fig. 21 isthat because of the extremely small sizes of the tips of the pole piecesthey must be very rigidly supported else they will not remain injuxtaposed position.

To insure positive alignment of the pole pieces of reduced size theconstruction shown in Figs. 23 and 24 may be employed, in which theopposite pole pieces H0 and III of iron, or other similar' paramagneticmaterial, are provided with tips H2 and I [3, respectively, of smallerdiameter than the recording wire I it but are enclosed and supported inreinforcing members I I5 and I it of nonmagnetic material, such as brassor aluminum. I'he reinforcing member H6 is provided with grooves Ill onits upper and lower sides, respectively, and the reinforcing member H5is provided with a pair of tongues H8 on its upper and lower sidesrespectively, which tongues extend into the grooves ill on thereinforcing member I I6, thereby preventing any relative displacementbetween the pole pieces I I2 and H3 in a vertical direction or in adirection longitudinal of the wire Ill while at the same time permittingmovement of pole pieces H2 and H3 toward each other as they are wornaway by the wire H4.

It is to be understood that the various pole pieces and coilconstructions shown in Figs. 14 to 24, inclusive, may be used for boththe erasing and recording and reproducing structures shown in Fig. 11.It is also to be understood that whereas in Fig. 11 the erasing corepiece 14 and the recording and'reproducing core piece III are rigidlymounted with respect to the wire 5, these core schematic diagrams ofFig. 12 and Fig. 13, re-' spectively, Fig. 12 showing the recordingcircuit and Fig. 13 thereproducing circuit.

Referring first to Fig. 12, we have shown the wire 5 moving firstbetween the pole pieces l2li I24 and I25 of therecording coils I23 and121,

respectively. A pair of'biasing coils I23 and I23 are also shownsurrounding the pole pieces I24 and I23, respectively. For purposes ofrepresentation, these coils I23 and I23 have beenshown mounted on therear ends of theirassociated pole pieces but it is to be understood thatin the actual construction of the coils the biasing coils will be woundon top of the recording coils.

Abattery I is connected in series with the two erasing coils I22 and I23and with a current limiting resistor I3I. A condenser I32 may beconnected in shunt across the erasing coils I22 and I23 and a condenserI33 may be connected across the current limiting resistor I3I. Thesecondensers I32 and I33 are optional but we have found that betterquality of reproduction is obtained by their use.

The battery I30 is also connected in series with the biasing .coils I23andv I29 through a current limiting resistor I34. The coils I28 and I29are preferably shuntedby acondenser I35 and the,

resistor I34 by a condenser I33, the use of these condensers improvingthe quality of reproduction.

The recording windings I23 and I2'I are connected in series through acondenser I33 and a resistor I33 to the output of an amplifier A to theinput of which amplifier there is connected a recording microphone I31.We have discovered that the insertion of the resistor I33 and thecondenser I33 in the recording coil circuit greatly improves thefidelity of reproduction obtained.

The current limiting resistor I3I in series with the battery I33 andtheerasing coils I22 and I23 is so proportioned relative to the coilsI22 and I23 and the potential ofvbattery I33 as to generate a constantmagnetic flux between the pole pieces m and m, sail! the steel wire 5 asit passes therebetween. This saturation of thewire not only erases anyprevious magnetic message that may exist on the wire but prepares it forthe next recording.

- The resistance I34 in series with the battery I33 and the biasingcoils I23 and I23 is of such value relative to the potential of thebattery and the constance of the coils I23 and I23, and these coilsaresopoledastoproduceinthereproducing corepieces I24 and I23 a constantmagnetic flux of such intensity and polarity as to reduce the magnetismin the saturated wire I to a value approximately half way between zeroand saturation. 'I henuxgeneratedbythevoicecurrentsinthe recording coilsI23 and I21 is superimposed on thisconstantiiux'byc oils I23andI23tov'arythe magnetism of above andl'ielow theccnstant value it wouldhave were no voice currents applied. Although we have not positivelyestablished the reason therefor, we have discovered that theuse oftheresistor I33, condenser I33 and the condenser I33 contribute greatlyto the quality of recordation obtained with the circuit.

lilthoughtheconstantsofthevariouselements inthecincuitofrlg. l2maybevariedhetwem wide limits, we have obtained excellent resultsemploying a resistor I33 of. 10,000 ohms, a condenser I33of .02microfarads, recording coik I23 and I21 of ohms impedance, biasing coshI23 and I23 of -'l0 ohms impedance, condensers I33 and I33 of .25microfarads, a battery I33 of 4% volts, resistor I34 of 2,000 ohmsresistance ing coils I22 and I23 of hmsistancetand.

I32 and I33 0!.23

cient to magnetically saturate output impedance of the amplifier A maybe approximately 500 ohms.

. In actual reproduction the same pole pieces and I coils thereon areused as were used for recording.

have reproducing coils I42 and I 43 thereon, which coils are connectedin series through a condenser I 44 to the input of an amplifier A, theoutput of the amplifier being connected to a loud speaker I45. Thiscircuit. is in accordance with conventionalpractice except for the useof the condenser I44 in series with the reproducing coils.

We have discovered that the use of this condenser contributes materiallyto the quality of reproduction of voice currents obtained.

In the recording and reproducing circuits of Figs. 12 and 13 theamplifier A may be of any conventional design to give sufficient gain toproduce the proper volume. Obviously, the input and output impedances ofthe amplifier should correspond approximately to the impedances of theapparatus connected thereto in accordance with well establishedpractice.

It is to be understood that the embodiments of the invention describedherein represent only a few of many possible variations and theinvention is to be limited only as set forth in the appended claims.

We claim: 1. In combination, a recording wire of high retentivity, arecording electroma'gnet, means for moving said wire past saidelectromagnet, a source of voice current to be recorded on said wire,and means for connecting said source to said recording electromagnet,said means including a condenser of substantial reactance at voicefrequencies connected in series with said recording electromagnet.

2. In combination, a recording wire of high retentivity, a recordingelectromagnet, means for moving said wire past said electromagnet, asource of voice current to be recorded on said-wire. and means forconnecting said source to said recording' 1 t, said means including acon-' denserandresistanceof ,tialreactanceat with said re- 4. Incombination, a..recording wire of high receptivity, an erasingelectromagnet and a recording electroma'gnet, means for moving said wirefirst p'astsaid erasing electromagnet and thereafter past said recordingeleetromagnet, a soule of voic'ecurrents to be recorded on said ""9meanscomprisingacoilonsaidelectromagnet connected to saidsource. meansfor apdirectcurrenttosaiderasingelectro--magnettosaturatesaidwireasitismovedpllt said erasing electromagnet. abiasing coil on said recording electromagnet, and means for supplyingdirect current thereto in such direction and ing coil on said recordingelectromagnet.

of such intensity as to partially demagnetize said saturated wire as itmoves therepast.

5. Apparatus as described in claim 4 inwhich j a by-pass condenser isshunted across said bias- 6. Apparatus as described in claim 4 in whicha by-pass condenser is connectedin shunt across said erasing coil.

7. Apparatus for use in .combination with a wire of high magneticretentivity having a magnetic record impressed thereon, comprising areproducing electromagnet, means for 'moving said wire past saidelectromagnet, electrically actuated means connected to saidelectromagnet for reproducing ,sound corresponding to currents inducedin said electromagnet by said wire, and a condenser connected in serieswith said electromagnet and said sound reproducing means.

8. Apparatus for use in combination with a wire of high magneticretentivity having a magnetic record impressed thereon, comprising areproducing electromagnet, means for moving said wire past saidelectromagnet, electrically actuated means connected. to saidelectromagnet for reproducing sound corresponding to currents induced insaid electromagnet by said wire, and a high pass filter means connectedbetween said electromagnet and said sound reproducing means.

9. In a telegraphone, means for moving and guiding a magnetic recordwire through a fixed path, a core piece of paramagnetic materialpositioned to contact said wire as it moves through said path, coilsupporting means rigidly attached to said core, a coil on said coilsupporting means, a frame member for supporting said coil supportingmeans and a rubber sheath between said 'coil supporting means and saidframe member for supporting the coil andcore with respect to the framepiece.

10. In a telegraphone, means for moving and guiding a record wirethrough a fixed path, a core piece of paramagnetic material forcooperating magnetically with said wire, said core piece beingpositioned in contact with said wire, a coil surrounding said core pieceand means for rigidly supporting said coil and core piece with respectto each other, a supporting frame, and means for movably supporting saidcoil and core supporting means in said frame for movement with said wirein response to transverse vibration of said wire.

11. In a telegraphone, means for moving and guiding a record wirethrough a fixed path, a core piece adapted to cooperate with said wire,a coil surrounding said core piece in magnetic relation thereto, meanfor supporting said coil and means for supporting said core within saidcoil comprising a rubber sh'eath'between said core piece and coilsupporting means.

12. In a telegraphone, means for supporting and guiding a recordwire'through a fixed path, a pair of core pieces positioned injuxtaposed relation on opposite sides of said wire, cooperating coilssurrounding said core pieces, and means for urging said core piecesagainst said wireon opposite sides thereof, said core pieces having tipportions for contacting said record wire, which tip portions are ofsubstantially the same transverse dimensions throughout their lengthand-of smaller dimensions transversely of said record wire than thediameter of said record wire.-

13. In a telegraphone, means for supporting and guiding a record wirethrough a fixed path, a core'piece positioned to contact with said wire,means for urging said core piece against said wire and a coilsurrounding said core piece, said core piece being of paramagneticmaterial of low retentivity substantially throughout except for the tipportion in'contact with said wire, said tip portion being hardened.

14. In a telegraphone, means for supporting and moving a record wirethrough a fixed path, a core piece positioned to contact with said wireat one end and a coil surrounding said core piece, said core piece beingof material of low magnetic retentivity throughout its major portion buthaving a hardened steel tip portion in contact with said wire.

15. In a telegraphone, means for guiding and moving a record wirethrough a fixed path, a pair of juxtaposed core pieces, having coilsmagnetically associated therewith, positioned to engage said wire onoppositesides thereof, and interlocking guide means on said core piecesfor maintaining said core pieces in juxtaposed relation independently ofsaid wire.

16. In a telegraphone, a recording and reproducing head, means forcontinuously moving a record wire through said head, said headcomprising a pair of armspositioned in the path of said wire, slits insaid arms for receiving said wire, and rotatable end members on saidarms also having slits therein whereby said wire may .be inserted insaid slits by rotating said end members to bring their slits intoregistration with the in the arms, and the wire thereafter locked inosition by rotating the end members to bring their slits out ofregistration with the slits in the arms.

17. In a telegraphone, a recording and reproducing head, means formoving a record wire through said head comprising a feed spool and awinding spool, reversible motor means for driving said spools, clutchmeans for automatically connecting said motor means'to said windingspool in response to rotation of said motor in one direction and forconnecting said motor to said feed spool to rewind the wire when themotor is operated in the opposite direction, the rotatable systemcomprising said motor means and either one of said spool means andconnecting mechanism having a moment of inertia substantially greaterthan the moment of inertia of either one of said spools, together withthe wire thereon, even when the spool is filled with record'wire.

18. In a telegraphone, a recording and reproducing head, a pair ofspools positioned on opposite sides of said recording head for feedingrecord wire through said recording head from one spool to the other, areversible motor for driving either one of said spools, and a clutchmechanism for selectively connecting saidmotor to one spool or the otheraccording to the direction' of rotation of the motor, said .clutch meanscomprising a pair of hub .members in driven relation with the motormeans,- one hub member having inclined the other having oppositelyinclined cam slots in its periphery, a pair of ring members surroundingsaid respective hubs, one of said ring members being connected indriving relation to one of said spools and the other being connected incam slots in its periphery and driving relation to the other of saidspools, balls spouse to movement or the'associated balls the shallowends of said cam slots.

19. In a telegraphone, a recording and reprointo ' ducing head, a pairof spools positioned on 0pposite -sides thereof for feeding wire throughsaid recording head, reversible motor means for,driving said spools, andclutch means for selectively amass! while permitting free radialmovement of said balls, a pair of ring members positioned concentricallyabout said respective retainers and connected respectively to said twospools, the balls in one retainer being adapted to lock the associatedhub and ring member together in re-- sponse to relative rotation betweensaid hub and associated retainer in one direction and the ballsassociated with the other hub being adapted to lock that hub to itsassociated surrounded ring member in response to relative rotationbetween that hub and ball retainer in vthe opposite direction, and meansfor locking said two retainers together.

GEORGE C. WOODMANSEE. CLaY G.- WOODMANSEE.

